If I __________ rich, I would help the poor.

The correct word to complete the sentence "If I __________ rich, I would help the poor" is "were." This sentence is an example of the second conditional, which is used to talk about hypothetical or unreal situations in the present or future and their probable results.

The structure of the second conditional is:

• If + simple past (for the condition)
• would + base form of the verb (for the result)

In the "if" clause of a second conditional, especially when expressing a wish or a hypothetical situation that is contrary to fact, the subjunctive mood is often used. For the verb "to be," this means using "were" for all subjects (I, he, she, it, we, you, they), not just plural ones. So, even with "I," we use "were" to indicate that the situation is not real.

Therefore, the correct sentence is: If I were rich, I would help the poor.